This proposal requests funds for the purchase of a Kratos MS-50/DS-90 FAB Mass Spectrometer system in order to provide state-of-the-art techniques for the identification and structural analysis of a variety of molecules with profound biomedical and chemical importance. This instrument would significantly promote the objectives of the research programs of the major users at SUNY at Stony Brook. In addition, it will advance the research of a large group of peripheral users and a group of biomedical scientists at Brookhaven National Laboratory. The MS-50/DS-90 instrument is an ultra high resolution mass spectrometer equipped with an inhomogeneous field RF magnet for extended mass range scanning to 10,000 daltons at full accelerating voltage. Necessary "soft" ionization techniques for the analysis of labile, non-volatile compounds will be furnished. FAB and a direct chemical ionization desorption system will be particularly important for ionizing biopolymeric compounds such as peptides, polysaccharides, and DNA oligimers. A capillary column gas chromatograph, linked B/E and B2/E metastable scanning, positive/negative ion detection, and a high speed data acquisition system (DS-90) are important accessories for the mass spectrometer system. The MS-50/DS-90 system will be located in the SUNY - Stony Brook Mass Spectrometer Facility and a nine member advisory committee will oversee the operation of the instrument. This mass spectrometer system will make directly available to investigators important new techniques for structural analysis of molecules, which are presently inaccessible or difficult and time consuming to obtain. It will accelerate research programs in many departments in the biomedical sciences at Stony Brook and Brookhaven National Laboratory.